A virtual finite state machine
is a finite state machine
(FSM) defined in a virtual environment. The VFSM concept provides a software specification method to describe the behaviour of a control system using assigned names of input control properties
and of output actions
The VFSM method introduces an execution model and facilitates the idea of an executable specification
. This technology is mainly used in complex machine control, instrumentation and telecommunication applications.
A variable in the VFSM environment may have one or more values which are relevant for the control – in such a case it is an input variable. Those values are the control properties of this variable. Control properties are not necessarily specific data values but are rather certain states of the variable. For instance, a digital variable could provide three control properties: TRUE, FALSE and UNKNOWN according to its possible boolean values. A numerical (analog) input variable has control properties such as: LOW, HIGH, OK, BAD, UNKNOWN according to its range of desired values. A timer can have its OVER state (time-out occurred) as its most significant control value; other values could be STOPPED, RUNNING etc...
A variable in the VFSM environment may be activated by actions - in such a case it is an output variable. For instance, a digital output has two actions: True and False. A numerical (analog) output variable has an action: Set. A timer which is... Read More